


Collision Course

by Get Dunked On (LittleKnownArtist), LittleKnownArtist



Category: Undertale (Video Game)
Genre: Alternate Universe - Underfell (Undertale), Anxiety Attacks, F/M, Fluff, Love Triangle, M/M, Multiverse, Nightmares, Other, Pansexual Character, Polyamory, Post-Traumatic Stress Disorder - PTSD, Recovery, Soriel, Touch-Starved, Underfell, Underfell Papyrus (Undertale), Underfell Sans (Undertale), Undertale Multiverse, becomes polyamory, cavities, everyone is pan okay, his brother making puppydog eyes at toriel, kustard - Freeform, kustard pie, m/f/m, papyrus is getting cavities and yuck everyone is so mushy, papyrus is living a nightmare, sans/toriel/sans, starts out as an obtuse love triangle, toriel/underfell sans, underfell sans/undertale toriel
Language: English
Status: In-Progress
Published: 2019-07-25
Updated: 2019-08-03
Packaged: 2020-07-19 12:53:56
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 4
Words: 9,477
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/19974400
Author URL: https://archiveofourown.org/users/LittleKnownArtist/pseuds/Get%20Dunked%20On, https://archiveofourown.org/users/LittleKnownArtist/pseuds/LittleKnownArtist
Summary: Red is desperate to save his brother after the human strikes him down. His injuries are near-fatal and he's being hunted. In a last-ditch effort, he manages to escape to another world. The version of his house he lands in isn't all that different, but it's completely empty, until two figures come stumbling in one day. Not the two that he had been expecting. Where is this world's Papyrus? Why does this Toriel make him feel so weak at the knees? What is up with his double, anyways?





	1. Well That Can't Be Good, Can It?

"shh, shh...boss, i gotcha..." Sans soothed his brother as he stabilized his neck as well as he could.

The strike had been quick, but Sans was faster, sending up bones in his desperation to deflect that creature's blows. He knew that thing was fast. He'd seen it strike down the birds. With terror coursing through his soul, he grew angry, pounding on that lady's door, asking what the fuck she'd been protecting. His fist made contact, and the door hit its frame and bounced back, ajar. The lady never left the door unlocked. She definitely wouldn't.

He stepped into the darkness, shoving the doors open to cast the lamplight on the entryway to the Ruins. His eyes grew wide. There was the pile of dust before the door, the tattered remains of a woman's black robes. Who had owned the robes? It couldn't be her, could it? He grasped at the fabric, examining it. She'd mentioned she was tall. He held it to him, and then...olfactory memories flooded back to him. Dreams he'd had which he knew weren't dreams after all. The smell of her pies, of her fur, of soot and...He saw her, it was a happier time, her chiding him like a child for taking so much pie for himself. Their arguments which ended with a cleverly worked in pun that diminished their anger in a moment. Tears working at his sockets from laughter.

That thing. That little worm. It had murdered her. It had murdered the drakes. It had...it had been heading straight for his brother! He knew Papyrus would go up against it. He had a feeling he knew more about that thing's capabilities than anyone else. He, somehow, with all the skill and strength and strategy that his brother possessed, he wouldn't stand a chance. He'd gotten there a second too late to shield him fully, so he did what he could. His brother was going down, but his soul was still intact. His bones had shielded Papyrus just enough to save his life. Sans threw up powdery snow to mask his presence and dove for his baby brother. The moment he had him cradled in his arms, he jolted through a shortcut.

He knew Undyne would hear about this soon. She'd be pounding on the door, demanding his head for unleashing that demon on the underground. His head. The joke wasn't lost on him as he had focused what little of his green magic as he could to healing the connections between his brother's cervical vertebrae, barely keeping his head attached. He heard the chaos just beyond his walls. Yelling, shrieking, screaming that sent ice spearing his soul. The human--that demon was looking for him. If Undyne didn't kill him first, that thing would. Either way, he needed an out.

He'd been fiddling with it for years. It was basically the only thing his father had ever left him. The calculations were only barely beginning to make sense, and Alphys hadn't made much more sense of it than he had, but what choice did he have?

He heard the traps outside his doors deploying. He wasn't sure if it was Undyne or that thing, but he figured if his dad's calculations were wrong, and it ended up exploding or something, well...he and Paps were dead either way.

His brother’s eyes were open and watching, but Papyrus’s voice hurt too much to utter more than a few words at a time. He laid motionless on the floor of the basement as Sans threw papers around, looking for the sheets with the hastily scrawled numbers series on it. Sans hoped the paralysis wasn’t permanent. He found the page with the information he needed shoved between the pages of his notebooks. Coordinates. He entered one of them at random. He didn’t care much where they ended up, so long as it wasn’t back in this hellhole.

He heard his front door smashed open. The machine buzzed to life. He gathered his brother in his arms, holding him like he hadn’t since the babybones Papyrus had stopped sucking on his thumb.

“ _arrivederci_ , ya pieces of shit!” 

* * *

“S…SAns…”

“c’mon boss. shuddup. save yer strength.”

“Ya hungry? One blink fer yeah, two fer nah.” Sans sighed as he watched his brother blink twice. Papyrus hadn’t been a prick to him once since Sans had drug them out of the other end of the portal into this world. That couldn’t be good. Being an asshole came naturally for Papyrus. Sans rested his head on the edge of the bed. It was Papyrus’s bed. Well, it looked exactly like the one Papyrus had owned until he was a teenager. How old was he when they had finally ditched the racecar bed for a more standard frame? Bah. Didn’t matter. Wherever Sans and Papyrus had landed, it obviously had a Papyrus. And a Sans for that matter—on a hunch, he’d tried his bedroom key in the door at the end of the hall, briefly inspecting the mess and the bare mattress. More liquor bottles lay scattered around than in his own room, but who’s to say another him wouldn’t be an alcoholic? He didn’t care. He wasn’t going to leave Papyrus’s side for long, not even to sleep. This house was virtually the same as their own, aside from the carpet, paint colors and condition of the furniture. Papyrus’s room—this Papyrus’s room—had the pirate flag and flame rug that Papyrus had.

Where the hell were this world’s Sans and Papyrus? There were cobwebs and dust—thankfully, not monster dust—covering much of the place. No one had been living here for a while. Maybe these brothers had been struck down by a human, too? The fridge was fully stocked with Tupperware full of spaghetti. Full. Of spaghetti. He and Papyrus didn’t have to leave this house for a while just from the stocks of food in the kitchen. He’d never seen so much food in one place, he’d whined with glee when he’d spotted the food. Not that the spaghetti was any good. But it was food, and he and Papyrus needed their strength. Sans had been putting all his effort into green magic. It was taking a lot out of him. He’d been sleeping nearly as much as the younger skeleton, head rested on the bed and hand gripping his brother’s wrist, so he’d know he was there. It felt so weird. He hadn’t touched his brother this much since they were kids, roughhousing, but…Papyrus couldn’t move. Sans had to take care of him, and that meant changing his bandages, sitting him up to eat, basically everything. At the same time, he felt like he needed to keep hold of Papyrus while they slept. He needed to know he was there. It was only beginning to finally crash over him how close Sans was to losing his baby brother. His only family. The only person in the whole world—the whole multiverse—he cared about.

He looked at Papyrus’s hand sadly. The only person still alive, that he cared about. He wasn’t ready to dwell on the loss of the voice behind the door. Not when Papyrus was still so weak. Papyrus needed his food well mashed with a fork. He could barely eat, and so Sans was doing his best to imbue the forkfuls of spaghetti with magic. They could hopefully deal with the taste and texture of it until Papyrus healed. So far they had put up with it for a few days. He hadn’t seen Papyrus making any progress yet…If it went on much longer, what would he do? He didn’t know if he could get a healer. He didn’t know what kind of world this was yet, he didn’t know if there was gold stashed under the floorboards to pay for one, either. He just had to hope, hope with all his soul that his green magic and Papyrus’s own will to live were enough to…

Papyrus didn’t wake up on the forth day. Sans was frantic. His green magic wasn’t enough. He’d let his brother fall into a coma. He was falling down, and Sans had to do something about it. He was tearing up the carpet and prying up floorboards, praying to whatever gods were listening that gold was under one of the usual ones. Papyrus needed help. He needed more help than Sans could offer.

Sans jolted to a quiet sound, the front door opening. He shot up at the sound. Shit. Someone was in the house. Shit! Papyrus was as quiet and still as Sans had left him. He was still breathing as he slept. Sans checked him. His soul was still holding together for now. Sans flew down the stairs, quiet as a cat, and bone attacks at the ready. He had to protect his brother. God. He just didn’t know what to do, but he had to keep on protecting him. He hid in the darkness, away from the windows. How they had broken the door in so quietly, he didn’t know. What he did know was that now that the door was open, the monsters—presumably looters targeting the dead brothers’ house—weren’t being quiet. A feminine giggle jolted Sans. God. That sounded familiar.

“oh geez,” a different voice said. It was male, deep—familiar? “this was a bad idea, tori. it’s dusty.”

“I mind less than you think.” Sans squinted as the pair emerged from the lighted doorway, and his vision adjusted. ‘ _Tori’_?

Then he saw her.

Big and white and beautiful. Sharp horns and fangs, and—just as he remembered her. He hadn’t been able to process her death with all that he had been dealing with at the time. Her laugh, her beautiful laugh. It tugged at his soul, constricting it and twisting a red-hot blade into its core. He remembered more dreams. He knew, seeing her now, that his dreams couldn’t have been dreams. Their relationship had been real. All the fights over nothing, all the nights spent talking together in front of the fire to ward off their nightmares, all the pranks, the puns. He had loved her, and she had loved him. The human had stripped all that away from him.

‘ _Toriel,_ ’ he mouthed.

But this Toriel wasn’t his Toriel. His Toriel had wild ruby eyes and black robes. This Toriel’s were a deep garnet, and her robes were a pristine violet color. That didn’t stop the wave of jealousy that swept over him when her arms wrapped around a smaller figure. He didn’t even register the monster’s face or type as she kissed his crown. The monster turned to kiss her neck in a way that was hardly chaste. Sans felt his face flush with anger.

“tori,” the smaller monster said when he pulled from her neck, “we’re drunk, and its dark, maybe we should head back towards the ruins?”

“Sans, I had at least hoped to see your old home, _if nothing else_. I can do something about the light.” As she said that, fireballs lit the corners of the room, exposing Sans to their gaze.

“Oh!” Toriel jumped in surprise. Tge other Sans followed her gaze, a surprised, confused expression on his features for a moment. Sans’s browbones knit, and he tightened his control on his bone attacks although he did not strike out. Despite the expression he wore, the look on his double’s face didn’t slip into fear. It shifted into nonchalance, and he buried his hands into the pockets of his blue hoodie, shifting to face the other skeleton, noticeably putting Toriel behind him.

“Who is..?” Toriel’s question didn’t finish.

“Dunno,” the other Sans shrugged, tipping his head to her, before focusing back on Sans. “Hey buddy, dunno how to tell ya this, but we’re wearing the same face. One of us is gonna have to go change.”

Realization struck Sans then. These weren’t looters. The skeleton was _him_. Meaning, he was a brother to a Papyrus. If he loved his brother anywhere near what Sans did, he could never harm Papyrus. Couldn’t even bring himself to attack a skeleton who so much as resembled Papyrus, no matter the world they came from. Sans’s face smoothed and his posture relaxed. For some reason, he felt more at ease. He knew Toriel with her bright, caring eyes, would do Papyrus no harm, either.

Maybe it was stupid, but…he felt like he could…these two…what was the word?


	2. Tori's Pretty Great if Ya Think About It

**Summary for the Chapter:**

> Toriel stabilizes Papyrus enough for him to begin healing on his own, enough for him to get his spark back. The four of them go back to the Ruins, where they'll be more comfortable.

Sans had a million questions on his mind, because of course he did. A guy wearing _his face_ was lurking in his old kitchen and glaring at him like he’d just bad-mouthed his mother. Bad-mouthed his mother after he’d just gotten back from a funeral. If the funeral was for a dog and their last wishes were for everyone to wear spiked dog collars to said funeral.

All of those questions left his mind and were replaced by dozens more once the guy said he was here with his brother. His brother, _Papyrus_. He tucked into a shortcut, landing at the door to his—what had been his—brother’s room. His breath caught in his chest cavity when he swung the door open.

He was there.

He was really there.

His brother was alive. His brother was whole. Sans felt his body trembling, taking a weary step forward. His baby brother! Except. It wasn’t. Sans exhaled the breath he’d been holding as he heard feet pounding up the stairs after him. He looked more carefully over the figure in the brighter light of the upstairs window. He took into account the scars, the sharper cheekbones, the sharpened teeth. It wasn’t really his brother, but…He looked so much like him. And he was hurt. He was hurt so badly. Used magic oozed into the bandages at his neck, the makeshift neck brace around the bandages. It wasn’t his brother, but that didn’t stop the knife that stabbed deeper into his soul at seeing the young skeleton in this state.

“Oh my God,” he heard Toriel gasp behind him. He stepped aside, Sans knew that tone. Toriel raced across the room, but not before Edgy McEdgerson cut her off. He stood in front of her, arms splayed out and snarling. Snarling!

“Lady, what the fuck do ya think—” He saw Toriel’s glare. It was a mother’s chastising glare, and it worked effectively against just about everyone. Even his grumpy little copy flinched. Sans stood straighter, seeing this. She had always held her own without issue. He loved that about her. Green magic swelled up around her palms and Sans watched his doppelgänger (pick a name for the guy, would ya? How about spike?) carefully. Spike’s browbones lifted in realization and he took a step to the side, letting Toriel past. Toriel shoved him further away as she knelt down beside Papyrus—not his Papyrus, he reminded himself.

Spike stood there, watching as Toriel’s magic swarmed over Papyrus’s body, most of it going to the wound around his neck. Sans observed quietly. Spike’s face was a little different now that he got a look at it in better lighting. Riddled with scars and cracks, the most noticeable extending from his forehead through his left socket and down to where one of his teeth had a gold crown. The other skeleton was fidgeting, too, and the fingers he used to pick at the hem of his coat were tipped with claw-like distal phalanges. Had he sharpened those himself? His teeth were sharp, too, but they fit together in a way that could only be natural.

Where the hell had these guys come from?

Spike (should he really go with that?) took several steps backwards when Toriel removed the bandages from Papyrus’s neck to work directly on the bones. The other skeleton all but collapsed into the computer chair when he backed into it. Sweat was beading on his brow, and he looked on nervously. Sans could feel his anxiety from where he stood. He could understand. Sans turned his gaze back to where Toriel was working on the tallest skeleton. She’d been tipsy and rather flirty the entire journey back here, but now she looked stone cold sober, focused entirely on the severely injured skeleton before her. God, that skeleton still had an uncanny resemblance to Papyrus.

Papyrus’s breathing changed, and he let out a pained sound. Spike jolted upright. Sans was next to him in a blink, laying a hand on his shoulder. The skeleton jerked in his grasp, but Sans squeezed his shoulder reassuringly.

“don’t worry, tori’s the best healer i know. if anyone can fix him up, it’s her.”

Spike glared at Sans, yanking his shoulder out of his grasp.

“yeah, well she better! or else, o-or else i’ll—i’ll…” He just finished his sentence with a scoff. He fidgeted for a second more before tucking his hands into his pockets.

Miraculously, Sans didn’t manage to dose off as he and the grumpy-looking skeleton watched Toriel and Papyrus. Sans noticed the guy was sweating pretty badly and he even smelled sort of sour. He'd asked the dude a few questions and had gotten terse, nondescript replies if he got anything more than a grunt at all. Talkative fellow. Though...he was waiting to see if his brother could be healed, it was no wonder he was on edge.

“Oh! Hello, are you awake?”

Spike leapt up at Toriel’s words. Sans tensed but settled when the grumpy little guy got on one side of Toriel, looking down at his brother.

“ah fuck bro, ya can’t be doin’ shit like that.” The smaller skeleton’s voice was noticeably higher in pitch, probably trying to hold back tears of joy.

“Wha…th fucksgoin on?” The voice was soft and crackly, and Sans couldn’t be sure if this was the guy’s normal voice or what. Probably not. The guy was clearly unwell and injured. It didn’t quite sound like his Papyrus, but then Sans couldn’t remember him getting sick since they were kids so he wouldn’t know what he sounded like in that sort of state.

“ah, bro. ya were tryna kick the bucket on me.” Sans walked closer as Toriel stood. The smaller of the scarred skeletons was gripping the sheets tightly, twisting them in his claws. Somewhere in the back of his head, Sans was annoyed that the guy might be tearing _his brother’s_ sheets, but he shook this off.

“Impossible,” the scarred Papyrus scoffed. Now he really did sound like Sans’s brother. Voice still crackly, but that unmistakable tenor, and that offended tone his brother had often used. This drove his previous questions back into his mind. These guys…they really were another him and another Papyrus, weren’t they? Where did they come from, and how exactly had they come here? The gears in Sans’s head clanked along as he watched everything from his spot, a knuckle pressed to his chin, contemplating. He had to admit, the trip through Grillby’s renovated bar wasn’t helping his processing capabilities. He still couldn’t help but use what clues he was getting to try to piece together possible scenarios for exactly how these current events had come to pass.

“yeah, you’d never die on me, would ya?”

Papyrus made a motion to show that he was rolling his eyes.

“KNOWING THE MESS YOU’D MAKE OF YOURSELF? HARDLY. YOU WOULDN’T SURVIVE WITHOUT ME.” His voice sounded much stronger now, and Sans felt himself struck by how similar it was to his brother’s, yet, it had a harsh quality to it. Papyrus had rarely used such a harsh tone, not unless he stubbed his toe unexpectedly or something.

“yeah, you’re prolly right, bro.”

Papyrus glared suddenly.

“SINCE WHEN HAVE YOU BEGUN ADDRESSING ME AS YOUR EQUAL, SANS?”

The smaller of the set chuckled darkly. Sans and Toriel’s eyebrows shot up. What kind of sibling dynamic was this, exactly?

“don’t ya remember? yer prolly out of a job now, you an me both.”

“ ** _WHAT?!_** ”

He obviously didn’t remember.

* * *

“We should let him sleep,” Toriel said softly, folding her hands in front of her. Sans had brought them all back to the Ruins, where it was warmer, and there was electricity. He sorta felt bad to realize that the two brothers had been eating cold spaghetti for four days now. Even Sans would have wanted to at least microwave it. As rude as they seemed to be, he couldn’t help but feel for whatever their situation was. He could guess that they had been through a lot, recently, and judging by the scars that littered their faces, they’d been through a lot in their lives, overall.

“he just got done sleepin’ fer like 16 fuckin’ hours!”

“heya, spike, buddy, mind not usin’ that kinda language towards the lady who just saved your bro’s life?” Sans’s gaze remained casual, but his tone conveyed the seriousness of his statement. The nasty fellow visibly bristled, clenching his jaw and beginning to growl lowly.

“Yes,” Toriel said, setting her hand atop the skeleton’s head. He squeaked and ducked away when she made contact. Sans watched Toriel blink in confusion. Guess he’d forgotten to tell her the guy seemed adverse to touch. Not that Sans cared. That was normally a gesture Toriel used on him when he was deep into his negative thoughts. He’d always thought it was an affection she’d reserved for him, so… Spike rubbed over his skull where Toriel had touched him, looking almost embarrassed before he seemed to reel himself in, stuffing his hands into his pockets and returning his face to what Sans supposed was neutral for him—a scowl.

Toriel sighed.

“We should all sleep soon. I have fully healed the cut in his neck, from here, he will only improve…” her voice trailed off, contemplatively.

“ya sure he’s fine now? he’ll be back ta normal?”

“I did not say that. I will continue to aid the healing process, but only time will tell if he will regain the function he once had.”

The scarred skeleton growled, but he seemed to accept that answer.

“Now…Before we sleep, you have not yet told us how he attained such a severe injury. I would also like to know…”

“why we look like two really ugly peas from the same pod,” Sans finished, gesturing between himself and his double.

“why ya gotta know? it makes no difference whether ya know or not.” Sans was going to say something in response but didn’t get to it quick enough.

“Well, you are a guest in my house now,” Toriel started, “while I would…certainly appreciate to know who I was keeping under my roof, I suppose it is not necessary…”

Sans and his double both stared up at the boss monster. Her soft smile and garnet eyes radiated warmth. It was a patient look. A look Sans had seen many times before, when he woke up startled and sweating. She did want answers, but she wasn’t going to pry too deeply. Not until he was ready. Sans glanced at the other skeleton from the corner of his socket. The skeleton blinked, once, twice, and Sans noticed that he seemed to be drawn in by Toriel, wholly focused on her glimmering red eyes. His browbone had smoothed some. Sans turned his head, to study the skeleton, but he didn’t seem to notice. The other guy saw only Toriel in that moment.

Something welled up in his soul then, for the second time in about a minute, this time, something stronger. He couldn’t exactly identify the feeling, but he didn’t suppose it was good. Maybe he’d know when he was completely sober. He shook it off as Toriel began to speak again.

“If you should decide to tell me, it can come later. It is rather late, and I have a headache starting, so tonight would not be for the best, after all.”

The other skeleton grunted in reply, dropping his gaze back to the ground, glaring at it.

Toriel offered him the third bedroom to sleep, but he shifted in his shoes, deciding to watch over his brother another night. The bed was the old king’s and plenty big enough for six or seven Sanses to sleep comfortably, so Sans thought it a bit strange that he curled up at Papyrus’s feet, but he could suit himself. Sans could…God, he missed Papyrus. He forced down a big glass of water and snuggled especially tight into Toriel’s soft form that night. She was so comfortable, and warm, and _his_.

* * *

The guy really did spill the beans come morning.

Toriel checked up on them early that morning. Papyrus couldn’t move yet, but he clearly still had feeling in his limbs, so that was good new for his recovery. Sans felt himself drawn to the skeleton that looked so, so much like his little brother. He thought the empty space in his soul had healed over the past year, but seeing the lanky, very Papyrus-sounding skeleton finding delight in Toriel’s breakfast cooking renewed the painful throbbing in his chest. How he had wished Papyrus would have the chance to taste her food. Her actual cooking, not just the botched recipes Sans had attempted over the years he’d spoken to her through the door. The scarred Papyrus took an instant liking to Toriel, praising her manners, asking his brother why it was so difficult for him to be polite. ~~His Papyrus would have liked her, too~~.

“damn bro, manners are sort of un- _man_ agable sometimes. I studied physics, not a- _polide_ psychology. They just don’t come _man_ -trually.”

God, those were the most terrible puns he’d ever heard in his life. So when he and Toriel couldn’t contain their laughter, it was no surprise. That got Spike laughing too.

“I SWEAR IF I COULD MOVE I WOULD MURDER YOU RIGHT NOW.” Welp. That was harsher than anything Papyrus had ever said to Sans, but the playful manner in which the guy got mad about shitty puns was _just_ like his brother had been.

“would it be murder or _manner_ slaughter, i wonder?”

“GET OUT OF MY SIGHT.”

The three of them left the scarred Papyrus to stew, to eat their own breakfast. Once they made it into the living room, Sans heard Spike make the sound of clearing his throat. He glared at a spot on the wall.

“Yes?” Toriel asked, tilting her head to the side. The other skeleton growled lowly, an annoyed sort of sound. He did that a lot, was it a habit, or was he genuinely angry 100% of the time?

“I’d say it was a long story, but it really ain’t.”

Sans quirked a browbone. He leaned over a chair, pulling it out for him. Toriel’s tactics worked on him every so often, but this guy had broken pretty quickly. Maybe he wasn’t used to people asking nicely.

“take a sit, buddy?” Sans asked.

Spike’s head tipped up, his eyelights scanned over Sans’s face for a moment before grunting again, shuffling over and plopping down in the chair. He made a lot of noises. Was this guy part bear or something?

“so, compared to what i seena this place…where me an’ Paps come from is really fuckin’ shitty in comparison,” he began.

**Notes for the Chapter:**

> I'm going to be switching between the three narratives, I hope it's clear when I start doing that next chapter. So far it's been Red for all of the first chapter and Sans for all of the second chapter. "Spike" will not be Red's permanent nickname, trust me. Ugh, there's so much set up involved in this fic, what with the universe crossovers. Still fun though.


	3. Just Grow Up and ACT Like An Adult

**Summary for the Chapter:**

> Red has a chat with Sans and Tori. Then Toriel gives him a lecture.

"i...figured it was probably the human," Sans said, his voice soft. Toriel looked over his features with concern rising through her soul. It hurt her to see him hurting. She, too, knew the pain of loss, and even though, for almost a year, he refused to say what had happened to his brother, Toriel knew. She could see it in his eyelights, their soft wavering when he got lost in thought, their inability to meet her eyes if the topic of his brother had ever come up. She had guessed. She had also guessed that it had been...Her child who had done that to him. She didn't want to believe it, and perhaps, in part, that was why she kept her silence about the issue. It was a horrendous conclusion to come to. But early on the morning he had told her, she put her head in her hands, and she believed every word of it. Every word of how her child had gone on to ravish the underground. She wanted to believe that that child was harmless, innocent and just scared, but to hurt someone like Papyrus. To strike him down while he held his arms open, ready to spare and befriend her child...

It was so horrible.

Papyrus had been a gentle soul, without a mean bone in his body. She had remembered how excited Sans had been the day Papyrus had graduated high school, telling her about how he had cried, because now Sans would let him try out to be in the Royal Guard.

She took a deep breath, exhaling and drawing her gaze back to the other skeleton. The one who looked and sounded so much like her Sans, but whose personality reflected one who had lived a much harder life. She was still mulling over his explanation of where he had come from, and what kind of world it had been. 'Kill or be killed,' he had said, and he had done what he could to keep himself and his brother alive all this time. She did not know what the scarred skeleton had meant by his father's machine, but a spark of recognition flickered within Sans, so she thought that he might explain in more depth to her later what the newcomer meant.

"so, the last human already come through these parts?" The scarred skeleton asked.

"Oh. Yes, they have come and...and left." Again, her soul tightened, conflicted. Her instincts were to protect her child, protect their honor, but she knew...

The scarred skeleton got a strange look on his face, suspicious, as he looked back over to Sans.

"ey, bluey. the fuck's your bro at?" He asked, pointedly, suspiciously. Sans tensed up. Toriel directed half-hearted glare back at the other skeleton. His tone was knowing.

"you fuckin' piece of shit." He glared. Sans looked back up. His brows were knit uncharacteristically.

"what?"

"you and me are nothin' alike, you fuckin' filthy piece of trash," he scoffed.

Sans's expression did not change.

"you let your brother die! you let that fuckin thing dust him?! i can't believe this shit!" the skeleton stood, glaring with his clawed hands tucked into his pockets. Toriel’s fists clenched in her lap.

"i'd NEVER let somethin' like that happen ta my bro. we may give each other shit, but damn--"His face crinkled in disgust.

"so..." Sans began softly. "i LET it happen, did i?"

Toriel's eyes darted for Sans's black sockets. Sans shrugged, but Toriel could read his face, the anger hidden beneath his nonchalance. Those words hurt. She was well aware of the guilt Sans had within his soul. Blaming himself, blaming himself for everything bad that had ever happened to him or his family. He was livid. Was it getting under his skin because it was someone who looked so similarly to himself that struck him so deeply? Because it sounded so similarly to his own voice that…

"am i speakin' italian here? _Si. e colpa vostra. Chi altro_?"

"maybe that's true. but what of it now? he's gone and i'm a piece of shit. you act like i haven't been telling myself this all along, _coglione._ "

Sans spoke Italian? Why was she not aware of this?

Toriel stood, feeling the prickle of smoke trailing from her nostrils as fire began to grow inside her. That was the thing she hated most, the type of self-deprecation Sans allowed to flow out of him. Because when he said it, he meant it, however flippant it sounded. The scarred skeleton's shoulders raised up around his neck, shrinking down into his bulky coat. Toriel saw sweat beaded up on his forehead, and a nervous expression was buried under all his aggression. His face was just as easy to read as her Sans's. He stared up at her, meeting her stern gaze, with wavering eyelights. Good, he understood. Sans almost looked surprised when she then turned her angered gaze to him, not understanding what he had done wrong.

"You are acting like children. Both of you. I have cared for many children in my life, human and monster, I would know. Do you not realize you are grown men? I will not tolerate schoolyard name-calling," her gaze struck Sans, and his posture came to resemble his scarred double's. Ashamed, embarrassed. These two were very much alike, indeed.

"From either of you."

She took a breath and her gaze softened.

"We have all made mistakes, done things we wished we had not, things we wished we had done differently. If you say you have not, you are lying to everyone around you, and to yourself. Now. May we eat the breakfast I made? It is likely already cold."

"m'not hungry," Sans muttered. She turned to him, but he was already scuttling around his scarred counterpart, down the hall.

"Sans," she called.

"save me some," he said back, no louder than his usual volume, but her large ears caught the request before he shut their bedroom door behind himself. She did not go charging after him. She might have in the past, but she had seen his mood shift like this many times over the past year she had known him face-to-face. He needed to be alone, just not too long. When she sighed, looking back to the scarred skeleton, she realized he, too, was no longer there. One brow lifted as she turned her head around to look for where he could have gone to. He had mentioned that his shortcuts did not seem to be working here, so she knew he could not have gone far.

Oh dear. These two. The scarred one had really hurt her Sans. She would need to have a private talk with him. From what she had seen, the two of them were more similar than they likely realized. The newcomer just…accentuated some of Sans’s more negative traits. It was like revisiting old demons, she realized. That was what it must have been like.

She caught a flash of black trailing into her kitchen and rounded the corner to find the scarred skeleton there. On top of her counter. Shoveling bacon and toast into his mouth. With his bare hands.

“Excuse me, I have plates and utensils you can use. I am sure that would be more pleasant than grease on your fingers,” she set a hand on her hip, pursing her lips. His head shot up to look at her, bacon dangling from his teeth and she jerked, seeing bright red rimming his sockets. Blood?! That was not right, what might make him bleed from the sockets?

“Are you…crying?”

“is sho goohd. whys ih tashe sho goohd?”

The scarred skeleton chose to forgo the utensils, but Toriel did get him to agree to eat at the table. Not that his table manners improved once he was sat at the table. Then again, Sans’s own were not that good when she first began eating meals with her. Nor were hers when she got a little wine in her, though that hardly counted. Toriel let him eat a few more bites. She would let him eat his fill and then she would cook a fresh meal for Sans when he was ready to eat. He really looked so enthusiastic about the meal. Come to think of it, so had the taller of the brothers. Toriel wondered how often it was that these two had a good home-cooked meal. Or any kind of significant meal. Kill or be killed where he was from meant that monsters fought over resources, food included. From his description, it…was a terrible place to grow up.

That did not excuse his behavior.

“You should know,” Toriel began, raising a brow, “what you said was completely reprehensible. You hurt Sans.”

The skeleton snorted into his food. He swallowed down his mouthful of toast.

“so? ya think i give a shit about his _feelings_?”

Toriel tapped her claws against the table. He was not even paying attention to her. His focus was almost entirely on the plate of food before him.

“You should.”

“bah, lady, let him ballbaby all he wants, it—that shit won’t change the fact that he’s failed as a brother. for fuck’s sake, i don’t even know his bro but just knowin’ he was a paps, makes my blood fuckin’ boi—HEY!” He reached for the plate that Toriel abruptly scooped up, holding it out of his reach. His expression was similar to that of a kicked puppy. He stood from his chair, leaning over the table, trying to reach the remaining bacon.

“h-hey. i-i wasn’t done yet.” He met her eyes, and she watched his eyelights constrict to pinpricks. Only for a moment, then they flared back larger than they had been. There was something, something strange in his expression. Like he had just recognized something within her own expression. He sat back down, keeping her gaze. Good. He was listening.

“Listen well. You will not talk that way to or about Sans, or there will be consequences. This is something you are familiar with, yes?”

His expression shifted to a slight glare. Toriel sighed, setting the bacon back on the table. He glanced at it for a moment, then returned his gaze, glare gone, in its place, confusion.

“It is…You said that you had barely come in time to save your brother from the last human? This means you almost did not come in time. It means—you could have lost him too.”

His shoulders hiked up around his neck. If he had fur, it would be standing on end.

“Have you thought about that? The difference that a single second could have made?”

He growled, breaking her gaze.

“’course i have.”

“Then I know you should have some sympathy—empathy for Sans’s situation. I will not tell you the—the amount of time Sans spent berating himself for the difference one single second made in his life.” She pressed a hand to her chest. “It hurts me, too. To know how he looks at himself.”

The skeleton looked back up, Toriel watching as emotions flitted behind his skeletal features. He was considering her words.

“And it pains me to hear you say such things.”

He growled.

“look, lady…” He only finished his sentence with another growl. He crossed his arms, much like a petulant child.

“ya want me to apologize?”

“As a start, yes. I should also hope that you realize…this is not the world you came from. You have no need to fight. No need to become so defensive over…” she touched a finger to her chin, trying to find her words.

“I do not know how long you intend on staying in this world, or if you plan on making this your new home, but…while you are here, and your brother is recovering, please just…”

“i getcha. look, i getcha.” He picked up a single piece of bacon. “i’ll…try. i can’t guarantee nothin’ though.”

Toriel nodded. She picked up her own toast, cold and soggy by that point. The skeleton ate slightly slower than he had before, his expression unreadable.

**Notes for the Chapter:**

> Next chapter has. A smidge of fluff. I think. I've only got 500 words written so idk for sure. But! Finally Red gets his moniker changed from "Spike"


	4. Nightmares Suck, What Else is New?

**Summary for the Chapter:**

> Red has a bad time,  
> then bed sharing trope.

**Notes for the Chapter:**

> Updated tags.

Sans, very pointedly, avoided the smaller of the skeleton brothers for the next day. Toriel was insistent that they have a chat, but he was still pissed for some reason. He didn't understand why it got _under his skin_. He didn't even have skin. He had already been through the grieving process. Guilt, apathy, trying to drink himself to death, standing on the edge of the abyss, wondering if it was all worth it. He'd been there already. He'd felt that he'd been given the responsibility to keep his brother safe, and he had failed. He had failed at everything that he did. His job at the lab, when he broke down after Gaster's pseudo-demise. His comedy bit at the hotel only kept hiring him because they charged 50G a tomato, and he was spectacular at dodging.

Damn, that guy. He just got him so riled up. He didn't understand how he'd done it. Toriel still voiced her opinion about the other skeleton. He seemed rough around the edges—the edgy bastard—but he was very much like him, she had told him. Hearing her say that—well, he can't claim it didn't _ruffle his feathers_. Again. He didn't have feathers. He felt regret the moment he realized he’d left Toriel alone with the guy. He didn’t even know him. It didn’t seem like he was lying, but Sans had been mistaken on rare occasions. He knew Toriel could handle herself, but he still didn’t know what kind of threat the guy posed.

Then she told him how he had cried tears of joy when he tasted her cooking. She told him that she wondered if he had ever had a decent meal in his life. She admitted that she was more than a little flattered to see someone have that reaction to her cooking.

"well, you've got the best cooking in the entire underground," Sans said. And he fully believed that, too. "i was damn near tears when i ate that first slice of pie you offered me."

He really had. Not just because it was so good, but because his brother wouldn't have the chance to taste it. He could probably learn a few things from Toriel, if she was up for the challenge of teaching him.

There he was on his brother again. He missed him. He really, truly, did. The other Papyrus was so much like him in a lot of ways. He talked about traps and death mazes a lot. It was certainly more lethal than his Papyrus's ideas, but he ranted about them with the same enthusiasm that his brother always had about his puzzles. From the time Papyrus was able to play with blocks, he made and completed maze puzzles. He wasn't the best at the final touches, but he did love making them. Sans's soul ached seeing this, strange, scarred doppelgänger of his brother talking exuberantly about his old plans and ideas. He even hated Hotland. They had a Hotland in that world, too, and he despised it just as much as his own brother had. Sans tried to avoid him too. Because it hurt to be around him.

Because he had let his own brother die.

Because that edgy prick was often at his side, just as Sans knew he would be if it were him and his Papyrus in their place. The guy didn’t come seeking him for conversation, so he was easy enough to avoid between work at his hotdog stand and collecting snails for Toriel.

But…

While Toriel’s ears worked well in the day, she absolutely slept like the dead. And that was a lot, coming from a skeleton. So, when Sans was awoken in the middle of the night to thumping sounds, he wasn’t surprised to see her soundly sleeping beside him. On the other side was Papyrus’s room, and on the side his bed was pushed against was the room Spike had finally slept in. It was definitely coming from the closest wall, meaning Papyrus was fine. He glared at the wall, wondering what the guy was up to. He rolled over, closing his eyes again.

Then, the thumps had been replaced by a different sort of sound. Vocal sounds. Sans sat back up, looking at the wall again. He stared at it as if he could see Spike on the other side. What was he doing? Sans knew he would regret it if the guy was just, uh, enjoying some alone time—it was the first time in a week he’d been apart from his bro, after all—but he pressed the side of his face to the wall. He listened closely. It was definitely whimpers, distressed sounding ones. Sans heaved a sigh of relief at that, before he realized that the guy was muttering something.

“m s’rry. m’ s’rry.” Sans heard. “pleasepleaseplease don’t.”

Something sharp twisted in Sans’s soul. Hearing a voice so similar to his own sounding pained, uttering those words…God, was this what Tori felt whenever she woke to him shivering? No, it was probably worse for her, because she loved Sans so much. Damn. He really felt for the guy right now. Well, very conflicted, at least. He was still pissed at him. Yet, recurring nightmares were something, it would seem, they shared. It wasn’t every night Sans would be plagued with them—some nights it was insomnia. He still knew the near-physical pain that waking up from one would bring. His head pounding, his soul throbbing, his chest tight, his whole body trembling.

He crossed his arms, tapping his fingers against his humeri. A pained moan came from the other side of the wall. This was going against his better judgement—heh, judgement—but…

A shortcut lead him to the third bedroom. As he suspected, sparks of red magic, unformed and harmless lit the room. In the center of the sparks was Spike, sitting in the center of the small bed, knees pulled to his chest and trembling. He had the blanket clenched tightly between his teeth, and tears were dripping from black sockets down his face, soaking into it.

“hey, hey, buddy,” Sans scrambled for the other skeleton, gripping ahold of his shoulders, “it’s not real, okay? you woke up.”

Spike tried half-heartedly to wrench himself from Sans’s hold. Sans shook him a little, trying to get the skeleton to look at him. It worked, two red pinpricks glinted from the black depths. He released the blanket from his teeth.

“oh sh-shit, oh fuck—j-j-just fuck-k-kin’—what the—get of-f-fa—” his ramblings came out stuttered, Sans knew he still wasn’t fully aware yet. He began trying harder to shove Sans away.

“hey, you’re fine.” He wrapped his arms around the skeleton’s shoulders, as Toriel had always done for him. He held his scarred counterpart’s wet face to his chest, feeling his heaving breaths against his shirt.

“let…let…”

Sans shushed him, rubbing his hand in circles down his back. Was he doing this right? This is how Tori had always done it, right? Granted, Tori was a lot cuddlier than he was. It must have been working, because Spike’s movements became less frantic. He sat on the bed, noticing that the sparks of errant magic had ceased.

“i know _exactly_ what you’re going through. it happens to me all the time. just—just take a second to breathe…you’re probably feeling really messed up right now, right?”

He got a grunt as his reply. At least he was listening. Sans sighed. This idiot. He could still feel his trembling against his fingertips, but he just kept on it, stroking the guy’s back. It still felt, sort of…weird, but. He really did know what he was going through. The accident at the lab—which he wasn’t sure was an accident—the vague nightmares of yellow flowers, the smell of dust, the face of the human as they struck down monster after monster…Sans felt a shiver of his own go down his back. The face of that thing was so cold. Emotionless. He still didn’t understand how Toriel had any sympathy for humans. Humans could live without Kindness, Hope, and Compassion, and from the only human he’d ever seen, it showed on their face. Even the face of a child. She’d told him that wasn’t the case. He’d only ever seen one human, so he only had that one to go off.

Even though, from what the guy had said, his brother hadn’t died yet, the tales he had about the kind of world he lived in…

He squeezed the guy a little tighter.

Dammit.

He was supposed to be mad at him. This guy had had such a shitty existence up until this point though. Almost made his boring life look like a walk through the forest compared. Almost.

“i’m sorry,” the guy mumbled.

“shh, it’s alright,” Sans attempted to soothe.

“no, not, uh. i’m fine now.” He pulled his head a little ways from Sans’s chest, looking down at the floor.

“for all the shit i said this morning.”

“oh.” Sans blinked. His hand stilled, Spike’s eyelights passed over his face before the returned to the ground.

“could ya, uh, keep doin’ that?” Sans raised a browbone, but complied, stroking back up and down his back. The guy’s face was beginning to get a smidge of pink on it. Hm. Was he embarrassed about needing his back rubbed? So, his aversion to touch that he had guessed earlier on, was it just because he didn’t get hugged enough as a kid. Wow, he was well on his way to being a supervillain. He thought about how easily he had caved when Toriel spoke kindly to him. Huh. Maybe he really wasn’t used to people being nice to him. Sans and his scarred double sat in silence for a few seconds. Sans was absorbing the…lackluster apology. Finally, he heard another grunt from Spike.

“i talked with, uh, well, i talked with tori and—toriel—and uh. i guess i was just kinda pissed with myself, and…”

“i was an easy target?” Sans offered. He eyed the other skeleton as the skeleton’s brows knit.

“i mean i guess? tori, though, she well…y-you know. i gave ya shit, but my brother…he uh. i was almost too late. then i really woulda been in your shoes.” He paused. Sans realized he was holding his breath.

“if we weren’t skeletons, if-if-if we w-were any other type of monster? a-a-a wound like that it, uh, it woulda. it woulda.” He coughed, Sans could tell it was getting hard for him to speak.

“it’d’ve been fatal,” Sans finished, finally letting out the breath he had been holding. Spike’s eyesockets shut tight at the admission. Sans continued rubbing down his back, noticing how tightly the bones were sitting together. He raised his hand to the back of Spike’s neck, earning opened eyesockets from the guy. He pressed between two vertebrae and—

“what’re ya—ohh…” The other skeleton visibly relaxed beneath his touch with the series of small popping noises within his spine.

“how’s that feel?”

“the fuck…” he sighed, straightening his back before hunching back over. “what’d ya? how’d ya know how ta do that?”

“we’re the same person, remember, spike?” The skeleton began to shrug, when he blinked.

“spike?”

“uh, yeah. it feels weird callin’ ya sans, since that’s my name.”

“what? oh come on, lotsa people got the same name, get the fuck over it.”

“well yeah, but get two daniels together and eventually one’ll go by dan.”

The other Sans raised a brow, thinking about it. He shrugged, halfheartedly agreeing.

“well then one of us need a nickname, and since i was here first, i been calling you spike.” The other skeleton glared. Although.

“yeah, that’s fair, but ‘spike?’ ya’ve gotta be shittin’ me with that name.”

* * *

The two of them debated nicknames back and forth until the found one which they could agree on. The newcomer’s natural magic, aside from his special attacks and healing magic was red, so, he agreed to that moniker, ‘Red’. They had argued for long enough that Sans was ready to pass back out, too lazy to move from the bed.

“say, red,” Sans said, sprawling across the bed, much to Red’s ire, “when’s the last time you showered? you smell bad.”

“if ya can’t stand my smell, get outta my bed.” He glared.

“didn’t say i couldn’t stand it. just, i’m sure a shower’d feel good.” Red raised a brow. Now that he thought of it, when he’d washed his hands after dinner…Toriel had hot water. Hot. Water. He couldn’t even remember the last time he’d had a hot shower. He’d always felt more miserable than usual after a cold shower back in his home world. She had a tub, too. He couldn’t reel in the excitement sparkling in his eyes, and Sans noticed.

“you can borrow some of my clothes, too. you’re not much smaller than me.”

“the fuck you mean ‘not much smaller’? we’re the same size!”

“nah,” Sans was already half asleep, snuggling into the pillow, “you’re like. two inches shorter.” Shit. Red had noticed something like that earlier on, but he was hoping it was just his imagination. He growled, shoving Sans by the shoulder.

“fine. whatever. just scootch over.” Sans rolled with ease, curled up and facing the wall.

Red woke to the creak of a door, and he opened his sockets just enough to see Toriel standing by the door, brow raised, a curious expression on her face. She bit her lip, contemplatively. Then she tilted her head to the side, and smiled, shutting the door. Red blushed furiously, looking down to find Sans sprawled out over the bed, arm thrown over his chest and head leaning against his spine—where his stomach would be if he had one. He shoved Sans off of him. He then tucked the blankets tightly around him, so that he couldn’t move or roll back over onto Red. Red then curled into a ball at the foot end, like a pet cat, and fell back asleep.

* * *

"OH MY GOD," Papyrus complained. Red had to hold in his laughter from the look on his brother's face as he ran the washcloth over his scapula. He felt all squeaky clean from the hot water (hot water, such a rare commodity back in his native Snowdin) and the borrowed clothes. He figured his brother was well overdue for a rinse, too, as much as Papyrus's hygiene usually mattered to him. The fact he couldn't bathe himself right now, well, the desire for cleanliness had weighed heavily on him, finally agreeing to this ‘procedure’ as Papyrus referred to it.

"THIS IS SO! SO! UNDIGNIFIED!" His cheekbones were flushed bright red, thoroughly embarrassed. 

"oh what," Red began, a mocking edge to his tone, "is you embawessed yer big bwother's got to see ya nakey" Red couldn't stop himself from cackling "—give it a rest, we used to take baths together as kids."

"WE HAVEN'T BEEN CHILDREN FOR SOME TIME, SANS!"

"so? you can't do this for yourself. would you rather have QUEEN TORIEL come do this instead?" Red could only laugh harder as he watched the entirety of his brother's skull engulfed in red. He was finally too embarrassed to speak at the thought of literal royalty having to give him a sponge bath. At least for a while.

"YOU SHOULD FIND SOMETHING TO DO," Papyrus suggested as Red scrubbed gently at his bottom-most ribs. 

"i'm almost done, fer fuck's sake."

"NO, I MEAN. IN GENERAL. I'VE ONLY SEEN YOU SCRIBBLING IN THAT BLASTED NOTEBOOK AND PLAYING GAMES ON YOUR PHONE THIS WHOLE TIME. AND SLEEP."

Red rolled his eyelights.

"A HOBBY, OR, AS MUCH AS IT WOULD PROBABLY TRAUMATIZE YOUR FRAGILE LAZY-ASS SOUL, A JOB. EVEN THAT OTHER YOU HAS A JOB!"

“yer not serious boss—bro—while you lie here wasting away? i’m here ta keep ya company.”

“SANS…I KNOW…about your nightmare last night…” his voice was softer at the end. Sans paused, reaching for the shirt Toriel has loaned Papyrus—way too big, but it’d have to do until the laundry was washed.

“…paps…”

“You know as well as I that they only come back when you have time for your mind to wander. SO! YOU NEED TO DO SOMETHING PRODUCTIVE DURING THE DAY.”

“like what? bro, this world’s in anarchy, they won’t take tori back as their queen, it’s not like i could go back to a royal army job, or hell, even a fuckin’ sentry job.”

“TORI?”

“it’s her nickname.”

“WELL, WHY DON’T YOU GO AND SEE WHAT SHE DOES DURING THE DAY? MAYBE YOU COULD OFFER HER ASSISTANCE IN…WHATEVER IT IS SHE DOES?”

Red raised a browbone. That…wasn’t a terrible idea, actually.

“i…yeah, maybe…”

He grumbled to himself, lifting Papyrus’s arms over his head so he could slip the shirt on. He laid him back down, standing to pull the covers back over his form. He pulled his arms out of the covers, Papyrus had been working on moving his fingers for a while. When he tried hard enough, he could tap them at his sides, moving them as if he were playing piano. His brother was going to recover yet.

**Notes for the Chapter:**

> SSSssliiight fluff. After this, I wonder what I'll do?  
> (author genuinely has no idea).

**Author's Note:**

> I've been meaning to write this for a while now. I call this ship "Kustard Pie" and Sans is a touch-starved little thing who, despite his best efforts, finds himself being drawn in by the small displays of affection that he's just not used to.


End file.
